E4F1真核表达载体的构建及与p53的相互作用

目的：构建E4 F1野生型及缺失32～81位氨基酸的真核表达载体，检测其与p53的相互作用及对下游基因p53的调节。方法分别用普通PCR和重组PCR方法从乳腺文库中扩增E4F1野生型编码序列及缺失32～81位氨基酸的突变型序列，分别将其以正确相位构建到pXJ40-MYC载体中，得到重组质粒MYC-E4F1和MYC-E4F1（Δ32-81），分别转化大肠杆菌DH5α，重组质粒经酶切鉴定并转染293 T细胞， Western印迹检测蛋白的表达。将MYC-E4F1和MYC-E4F1（Δ32-81）质粒与FLAG-p53质粒共转染293T 细胞，免疫共沉淀实验检测其相互作用，野生型及缺失突变型表达载体共转染骨肉瘤细胞U2OS，检测其对下游基因p53的调节。结果 E4F1重组质粒及其突变型构建成功，在293 T细胞中鉴定表达正确，野生型及突变型E4 F1均与p53存在相互作用，突变型的结合能力增强，野生型E4F1升高p21蛋白表达水平，而突变型不改变p21蛋白水平。结论成功构建E4F1野生型及缺失32～81位氨基酸的突变型真核表达载体，二者都能与p53相互作用且突变型结合能力更强，野生型E4F1升高基因p53的靶基因p21的蛋白表达水平，而突变型不改变靶基因p21的蛋白水平。该研究为进一步研究E4 F1对p53的调节及其机制奠定了基础。

Construction of eukaryotic expression vector of E4F1 and interactions between E4F1 and p53

Objective To construct eukaryotic expression vector of wild type E 4F1 and the mutant deleting amino acid region 32-81, and to detect the interaction between wild type or mutant E 4F1 and p53 and to study the effect of E4F1 on the expression level of p21.Methods Wild type and mutant sequences of E 4F1 were amplified from the mammary library using standard PCR and recombinant PCR .The sequences were cloned into pXJ 40-MYC vector to generate the MYC-E4F1 and MYC-E4F1（Δ32-81） recombinant plasmids that were transfected into 293T cells and identified by Western blotting . FLAG-p53 and MYC-E4F1 or MYC-E4F1（Δ32-81） were co-transfected into 293T cells and immunoprecipitation assay was performed to detect the interaction of wild type or mutant E 4F1 with p53.Wild type and mutant E4F1 expressing vec-tors were co-transfected into osteosarcoma U2OS cells and the expression of p21was detected.Results Recombinant plas-mids of MYC-E4F1 and MYC-E4F1（Δ32-81） were successfully constructed.Both wild type and mutant E4F1 interacted with p53.Deletion of amino acid region 32-81 of E4F1 increased the interaction .The expression level of p21 was in-creased by wild-type E4F1, but not by mutant E4F1.Conclusion The eukaryotic expression vector of wild type E4F1 and its deletion mutant is successfully constructed .Both of them interact with p53.Deletion of amino acid region 32-81 of E4F1 increases the interaction .This study contributes to further studies on the regulation and mechanism of E 4F1 on p53.